1. Field of the Invention
The present invention relates to a lead frame for use in connecting motor coils of an electric motor used on, for example, a hybrid vehicle and a distributing part using the same lead frame.
2. Description of the Related Art
In the related art, a distributing part for use in connecting motor coils is fabricated, for example, in a process described below.
Firstly, as shown in FIG. 16A, a copper plate 44 which is cut to a desired size is prepared, and by applying a press blanking process to this copper plate 44, frame parts 46U, 46V, 46W shown in FIG. 16B are formed. Next, by applying a bending process to these frame parts 46U, 46V, 46W, lead frames 41U, 41V, 41W shown in FIG. 16C are formed. Then, these lead frames 41U, 41V, 41W are set in a mold in a state in which the lead frames are stacked on each other in such a manner as to provide a gap therebetween, and by molding a molding resin (an engineering plastic) through injection molding, the respective lead frames are integrated together in an insulated state to thereby fabricate a distributing part. A similar construction to this is shown in, for example, JP-A-2001-25198.
The motor coils (not shown) are connected to terminal portions 42 formed on the respective lead frames 41 via connecting parts by virtue of fusing (sport welding) or soldering. In addition, polyphenylene sulfide (PPS) or liquid crystal polymer (LCP) is used for the molding resin. In the illustrated example, six terminal portions 42 are provided for U, V and W phases, respectively. Note that reference numeral 43 denotes feeding terminal portions for feeding current the respective lead frames for the U, V and W phases.
Incidentally, in a large motor in which the diameter of a stator, for example, becomes 150 mm or greater, the distributing part used in this motor becomes large and current to be conducted is increased. Therefore, in the event that the motor is operated, the temperature of the respective lead frames 41U, 41V, 41W increases, and this leads to an increase in temperature of the molding resin. Since the molding resin is molded under a high injection pressure, the resin so molded adheres to the lead frames to thereby provide an integral construction. Thus, in the event that the distributing part deforms due to heat, there is caused a problem that a large strain is generated between the copper lead frames and the molding resin due to a difference in coefficient of thermal expansion therebetween.
In addition, as shown in FIG. 16B, in a case where the lead frames 41U, 41V, 41W are formed by press blanking or cutting the copper plate 44, a waste part 45 of the copper plate becomes large. Hence, the loss of the material becomes large, there is caused a problem that the yield is deteriorated and the production costs are increased. In particular, when the distributing part becomes large, the size and thickness of the copper plate 44 are increased, and this remarkably increases the loss of the material.